The present invention relates to a compact cross-channel mixer having several stacked foils whereby flow channels are formed due to a special design of the foils, e.g., a sine wave design, and whereby the flow channels of foils that are positioned on top of each other cross each other.
A cross-channel mixer is known from WO 91/16 970, in which each mixing element is composed of a foil package. The foils are provided with a corrugated shape so that flow channels are formed when the foils are stacked onto each other. These flow channels are positioned cross-wise when the foils are stacked. When mixtures of fluids and suspended solids flow through, homogenizing occurs in the stacking plane. In order to achieve a thorough mixing in the radial and circumferential direction, several, however at least two, of these equally designed mixing elements are tacked on top of each other such that their stacking planes are rotated, e.g. by 90xc2x0. Because of two or more mixing elements arranged in series, such a mixer is not only expensive but also requires a large mounting space, which causes problems with respect to the available mounting space, e.g., when they are mounted into exhaust gas systems of motor vehicles.
In contrast thereto, it is an object of the present invention to develop a cross-channel mixer which consists of a single mixing element only, however still achieves good homogenizing across the entire cross section.
This object is solved by the inventive cross-channel mixer in that the foils, which are stacked to form a mixing element, are rotated about the main flow direction.
By rotating the stacked foils about the main flow direction, a good mixing in the radial direction and in the circumferential direction is achieved without the necessity of stacking two or more mixing elements on top of one another.
It is advantageous to vary the gradient of the flow channels in order to facilitate machining of the foils because they have a tendency to shift off laterally when they are rolled at a steeper gradient.
An advantageous rotation is achieved when the foils are rotated about the main flow direction in an S-shape. Inhomogeneous fluid/suspended solids-mixtures applied in the vicinity of the axis of the mixing elements are distributed about the entire cross-sectional surface and are homogenized. Furthermore, the mixing path is expanded by the rotation.
A further advantageous embodiment is achieved when the wave crests of the stacked foils forming the flow channels are provided with slots at an angle relative to their main extension direction. An improvement in the radial mixing action is achieved by the slots.
The chemical reactions can be activated by coating the foils with a catalyst.